Re: [PyOpenGL-Users] Pyopengl - slow performance using

[Ian M. <geo...@gm...>]

On Thu, Jan 13, 2011 at 7:45 PM, Chris Barker <Chr...@no...> wrote:

> On 1/13/2011 3:17 PM, Ian Mallett wrote:
> >      > doing this. Python lists are just linked lists,
> >
> >     no, they are not -- they are internally regular C arrays.
> >
> > But they are resizable, which implies they are either linked lists or
> > array lists--because I doubt the pointers are copied over to a brand-new
> > array just big enough each time a single element is added or removed.
>
> A bit OT, but they handle re-sizing by over allocating when appended to.
> So most of the time you can append to a list without any memory
> allocation or copying, but as it grows, it does need to do that once in
> a while.
>
Right--this data structure is called an array list.

You're absolutely correct that Python users should avoid it for very high
performance.  I usually stick with NumPy arrays for all but the most dead
simple stuff.  They also tend to be compatible with other packages--in
particular, I've used them to tie very nicely into PyOpenGL's VBO class:

my_vbo = vbo.VBO(numpy_1x3_array,'f')

In fact, they seemed to be the only thing that actually did work.  And,
speed aside, NumPy provides some truly great functionality when it comes to
working with arrays--like element-wise operations, anyone?

Ian